Pen



FIG. 1 is a perspective view of a pen, showing my new design;

FIG. 2 is a front elevation view thereof;

FIG. 3 is a rear elevation view thereof;

FIG. 4 is a right elevation view thereof;

FIG. 5 is a left elevation view thereof;

FIG. 6 is a top view thereof; and,

FIG. 7 is a bottom view thereof.

The broken lines showing the barrel and clip of the pen in FIGS. 1-7 are included for the purpose of illustrating portions that form no part of the claimed design. 

The ornamental design for a pen, as shown and described. 